DS1340Z-33 Real Time Clock IC: Equivalent & Substitute Parts

Part Overview

The DS1340Z-33 is a Real Time Clock (RTC) IC with Clock/Calendar functionality, featuring I2C 2-Wire Serial interface in an 8-SOIC package. This component provides timekeeping with leap year support and trickle-charger capability across a supply voltage range of 2.97V to 5.5V, with battery backup operation from 1.3V to 5.5V. The DS1340Z-33 is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. Substitute components must maintain functional compatibility through matching interface protocols, package form factors, and electrical operating parameters.

Key Parameters

Parameter	DS1340Z-33 Specification
Interface	I2C, 2-Wire Serial
Package / Case	8-SOIC (0.154", 3.90mm Width)
Voltage - Supply	2.97V ~ 5.5V
Voltage - Supply, Battery	1.3V ~ 5.5V
Time Format	HH:MM:SS (24 hr)
Date Format	YY-MM-DD-dd
Operating Temperature	-40°C ~ 85°C
Current - Timekeeping (Max)	150µA @ 5.5V
Mounting Type	Surface Mount
Type	Clock/Calendar

Substitute Part Grouping Explanation

Substitution for the DS1340Z-33 is determined by the following critical parameters:

Primary Compatibility Criteria:

Interface protocol: I2C, 2-Wire Serial (mandatory)
Package form factor: 8-SOIC (0.154", 3.90mm Width) or compatible 8-pin surface mount packages
Supply voltage range: Minimum 2.97V support required
Battery backup voltage: Minimum 1.3V support required
Operating temperature range: -40°C to 85°C
Time/Date format: HH:MM:SS and YY-MM-DD-dd support

Substitute Categories:

Direct Equivalent (Same Package, Same Manufacturer): DS1340Z-33+ is the direct successor with identical electrical and mechanical specifications, differing only in product status (Active vs. Obsolete) and RoHS compliance (ROHS3 Compliant vs. non-compliant).

Manufacturer-Recommended Alternatives (8-SOIC Package): 1338-31DCGI, 1339-31DCGI, and 1339-31DCGI8 from Renesas Electronics Corporation maintain the 8-SOIC package and I2C interface. These parts support 12/24-hour time format and include additional features such as NVSRAM and square wave output.

Cross-Manufacturer Alternatives (8-SOIC Package): ISL12008IB8Z and ISL12008IB8Z-T from Renesas Electronics Corporation provide 8-SOIC packaging with I2C interface and extended battery backup voltage range (1.8V ~ 5.5V).

Alternative Package Options (8-TSSOP / 8-MSOP): 1337GDVGI8 (8-MSOP) and BU9873FVT-GE2 (8-TSSOP) offer reduced package footprint while maintaining I2C interface and core RTC functionality. These require PCB layout adjustment due to different package dimensions.

Extended Functionality Option (20-SOIC Package): ISL12022MAIBZ-T provides enhanced memory (128B SRAM) and additional features in a larger 20-SOIC package, suitable for applications requiring expanded data storage.

Parameter Comparison

Part Number	Manufacturer	Package	Supply Voltage	Battery Voltage	Interface	Time Format	Current - Timekeeping (Max)	Product Status	RoHS Status
DS1340Z-33	Analog Devices Inc./Maxim Integrated	8-SOIC	2.97V ~ 5.5V	1.3V ~ 5.5V	I2C, 2-Wire Serial	HH:MM:SS (24 hr)	150µA @ 5.5V	Obsolete	RoHS non-compliant
DS1340Z-33+	Analog Devices Inc./Maxim Integrated	8-SOIC	2.97V ~ 5.5V	1.3V ~ 5.5V	I2C, 2-Wire Serial	HH:MM:SS (24 hr)	150µA @ 5.5V	Active	ROHS3 Compliant
1338-31DCGI	Renesas Electronics Corporation	8-SOIC	3.3V ~ 5.5V	1.3V ~ 3.7V	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	5µA @ 3.63V ~ 5.5V	Active	ROHS3 Compliant
1339-31DCGI	Renesas Electronics Corporation	8-SOIC	3.3V ~ 5.5V	1.3V ~ 3.7V	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	200µA @ 3.63V ~ 5.5V	Active	ROHS3 Compliant
1339-31DCGI8	Renesas Electronics Corporation	8-SOIC	3.3V ~ 5.5V	1.3V ~ 3.7V	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	200µA @ 3.63V ~ 5.5V	Active	ROHS3 Compliant
ISL12008IB8Z	Renesas Electronics Corporation	8-SOIC	2.7V ~ 5.5V	1.8V ~ 5.5V	I2C, 2-Wire Serial	HH:MM:SS:hh (24 hr)	4µA ~ 6µA @ 3V ~ 5V	Active	ROHS3 Compliant
ISL12008IB8Z-T	Renesas Electronics Corporation	8-SOIC	2.7V ~ 5.5V	1.8V ~ 5.5V	I2C, 2-Wire Serial	HH:MM:SS:hh (24 hr)	4µA ~ 6µA @ 3V ~ 5V	Active	ROHS3 Compliant
1337GDVGI8	Renesas Electronics Corporation	8-MSOP	1.8V ~ 5.5V	—	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	0.6µA @ 1.3V ~ 1.8V	Active	ROHS3 Compliant
BU9873FVT-GE2	Rohm Semiconductor	8-TSSOP	1.8V ~ 5.5V	—	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	1µA ~ 1.35µA @ 3V ~ 5.5V	Not For New Designs	ROHS3 Compliant
ISL12022MAIBZ-T	Renesas Electronics Corporation	20-SOIC	2.7V ~ 5.5V	1.8V ~ 5.5V	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	14µA ~ 15µA @ 3V ~ 5V	Active	ROHS3 Compliant
ISL12026AIVZ	Renesas Electronics Corporation	8-TSSOP	2.7V ~ 5.5V	1.8V ~ 5.5V	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	10µA ~ 20µA @ 2.7V ~ 5.5V	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Functionality): DS1340Z-33+ is the primary recommendation as the active successor to the obsolete DS1340Z-33. It maintains identical electrical specifications and 8-SOIC package form factor. The upgrade to ROHS3 compliance addresses regulatory requirements for new production.

For 8-SOIC Package Alternatives: 1338-31DCGI and 1339-31DCGI series from Renesas provide active product status with ROHS3 compliance. Note that minimum supply voltage is 3.3V (versus 2.97V for DS1340Z-33), which may require circuit redesign in low-voltage applications. The 1338-31DCGI includes 56B NVSRAM for applications requiring non-volatile storage.

For Low-Power Applications: ISL12008IB8Z and ISL12008IB8Z-T offer significantly reduced timekeeping current (4µA ~ 6µA) compared to the DS1340Z-33 (150µA), making them suitable for battery-powered designs. These parts maintain 8-SOIC packaging and support extended battery voltage range (1.8V ~ 5.5V).

For Compact Footprint: 1337GDVGI8 (8-MSOP) and ISL12026AIVZ (8-TSSOP) reduce package size while maintaining I2C interface and core RTC functionality. These require PCB layout modification and are suitable for space-constrained applications.

For Extended Memory Requirements: ISL12022MAIBZ-T provides 128B SRAM in a 20-SOIC package, supporting applications requiring integrated data storage beyond timekeeping functions.

Avoid for New Designs: BU9873FVT-GE2 carries "Not For New Designs" status despite ROHS3 compliance and should be used only for legacy system maintenance.

Frequently Asked Questions (FAQ)

Q: Can DS1340Z-33+ be used as a direct drop-in replacement for DS1340Z-33? A: Yes. DS1340Z-33+ maintains identical electrical specifications, package form factor (8-SOIC), and functional characteristics. The primary differences are product status (Active vs. Obsolete) and RoHS compliance level (ROHS3 vs. non-compliant).

Q: What is the minimum supply voltage requirement for Renesas 1338-31DCGI and 1339-31DCGI alternatives? A: Both parts require minimum 3.3V supply voltage, compared to 2.97V for the DS1340Z-33. Applications operating below 3.3V require alternative parts such as ISL12008IB8Z (2.7V minimum) or 1337GDVGI8 (1.8V minimum).

Q: Are 8-MSOP and 8-TSSOP packages compatible with 8-SOIC PCB layouts? A: No. While all are 8-pin surface mount packages, they have different pin spacing and footprints. 1337GDVGI8 (8-MSOP, 3.00mm width) and BU9873FVT-GE2 (8-TSSOP, 4.40mm width) require dedicated PCB layouts distinct from 8-SOIC (3.90mm width) designs.

Q: Which substitute part offers the lowest timekeeping current consumption? A: 1337GDVGI8 provides the lowest timekeeping current at 0.6µA @ 1.3V ~ 1.8V. ISL12008IB8Z and ISL12008IB8Z-T offer 4µA ~ 6µA @ 3V ~ 5V, significantly lower than the DS1340Z-33 at 150µA @ 5.5V.

Q: Does ISL12022MAIBZ-T require different firmware or software support compared to DS1340Z-33? A: ISL12022MAIBZ-T maintains I2C 2-Wire Serial interface and standard RTC register architecture compatible with DS1340Z-33 software. The primary difference is the addition of 128B SRAM, which is optional and does not affect basic timekeeping functionality.

Q: What is the battery backup voltage range for each substitute part? A: DS1340Z-33+ and ISL12008 series support 1.3V ~ 5.5V and 1.8V ~ 5.5V respectively. Renesas 1338-31DCGI, 1339-31DCGI, and 1339-31DCGI8 support 1.3V ~ 3.7V. BU9873FVT-GE2 and 1337GDVGI8 do not specify battery backup voltage. Verify battery backup requirements before selection.

Q: Is RoHS3 compliance mandatory for new designs? A: RoHS3 compliance is required for products sold in EU markets and increasingly in other regions. All recommended active alternatives (DS1340Z-33+, Renesas 1338-31DCGI series, ISL12008 series, ISL12022MAIBZ-T, ISL12026AIVZ) carry ROHS3 Compliant status. BU9873FVT-GE2 is ROHS3 compliant but marked "Not For New Designs."

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